subr_trap.c

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    1 /*-
    2  * Copyright (C) 1994, David Greenman
    3  * Copyright (c) 1990, 1993
    4  *      The Regents of the University of California.  All rights reserved.
    5  * Copyright (c) 2007 The FreeBSD Foundation
    6  *
    7  * This code is derived from software contributed to Berkeley by
    8  * the University of Utah, and William Jolitz.
    9  *
   10  * Portions of this software were developed by A. Joseph Koshy under
   11  * sponsorship from the FreeBSD Foundation and Google, Inc.
   12  *
   13  * Redistribution and use in source and binary forms, with or without
   14  * modification, are permitted provided that the following conditions
   15  * are met:
   16  * 1. Redistributions of source code must retain the above copyright
   17  *    notice, this list of conditions and the following disclaimer.
   18  * 2. Redistributions in binary form must reproduce the above copyright
   19  *    notice, this list of conditions and the following disclaimer in the
   20  *    documentation and/or other materials provided with the distribution.
   21  * 3. All advertising materials mentioning features or use of this software
   22  *    must display the following acknowledgement:
   23  *      This product includes software developed by the University of
   24  *      California, Berkeley and its contributors.
   25  * 4. Neither the name of the University nor the names of its contributors
   26  *    may be used to endorse or promote products derived from this software
   27  *    without specific prior written permission.
   28  *
   29  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   30  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   31  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   32  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   33  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   34  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   35  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   36  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   37  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   38  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   39  * SUCH DAMAGE.
   40  *
   41  *      from: @(#)trap.c        7.4 (Berkeley) 5/13/91
   42  */
   43 
   44 #include <sys/cdefs.h>
   45 __FBSDID("$FreeBSD: releng/8.0/sys/kern/subr_trap.c 195702 2009-07-14 22:52:46Z kib $");
   46 
   47 #include "opt_ktrace.h"
   48 #ifdef __i386__
   49 #include "opt_npx.h"
   50 #endif
   51 #include "opt_sched.h"
   52 
   53 #include <sys/param.h>
   54 #include <sys/bus.h>
   55 #include <sys/kernel.h>
   56 #include <sys/lock.h>
   57 #include <sys/mutex.h>
   58 #include <sys/pmckern.h>
   59 #include <sys/proc.h>
   60 #include <sys/ktr.h>
   61 #include <sys/resourcevar.h>
   62 #include <sys/sched.h>
   63 #include <sys/signalvar.h>
   64 #include <sys/systm.h>
   65 #include <sys/vmmeter.h>
   66 #ifdef KTRACE
   67 #include <sys/uio.h>
   68 #include <sys/ktrace.h>
   69 #endif
   70 
   71 #include <machine/cpu.h>
   72 #include <machine/pcb.h>
   73 
   74 #ifdef XEN
   75 #include <vm/vm.h>
   76 #include <vm/vm_param.h>
   77 #include <vm/pmap.h>
   78 #endif
   79 
   80 #include <security/mac/mac_framework.h>
   81 
   82 /*
   83  * Define the code needed before returning to user mode, for trap and
   84  * syscall.
   85  */
   86 void
   87 userret(struct thread *td, struct trapframe *frame)
   88 {
   89         struct proc *p = td->td_proc;
   90 
   91         CTR3(KTR_SYSC, "userret: thread %p (pid %d, %s)", td, p->p_pid,
   92             td->td_name);
   93 #ifdef DIAGNOSTIC
   94         /* Check that we called signotify() enough. */
   95         PROC_LOCK(p);
   96         thread_lock(td);
   97         if (SIGPENDING(td) && ((td->td_flags & TDF_NEEDSIGCHK) == 0 ||
   98             (td->td_flags & TDF_ASTPENDING) == 0))
   99                 printf("failed to set signal flags properly for ast()\n");
  100         thread_unlock(td);
  101         PROC_UNLOCK(p);
  102 #endif
  103 #ifdef KTRACE
  104         KTRUSERRET(td);
  105 #endif
  106         /*
  107          * If this thread tickled GEOM, we need to wait for the giggling to
  108          * stop before we return to userland
  109          */
  110         if (td->td_pflags & TDP_GEOM)
  111                 g_waitidle();
  112 
  113         /*
  114          * Charge system time if profiling.
  115          */
  116         if (p->p_flag & P_PROFIL) {
  117                 addupc_task(td, TRAPF_PC(frame), td->td_pticks * psratio);
  118         }
  119         /*
  120          * Let the scheduler adjust our priority etc.
  121          */
  122         sched_userret(td);
  123         KASSERT(td->td_locks == 0,
  124             ("userret: Returning with %d locks held.", td->td_locks));
  125 #ifdef XEN
  126         PT_UPDATES_FLUSH();
  127 #endif
  128 }
  129 
  130 /*
  131  * Process an asynchronous software trap.
  132  * This is relatively easy.
  133  * This function will return with preemption disabled.
  134  */
  135 void
  136 ast(struct trapframe *framep)
  137 {
  138         struct thread *td;
  139         struct proc *p;
  140         int flags;
  141         int sig;
  142 #if defined(DEV_NPX) && !defined(SMP)
  143         int ucode;
  144         ksiginfo_t ksi;
  145 #endif
  146 
  147         td = curthread;
  148         p = td->td_proc;
  149 
  150         CTR3(KTR_SYSC, "ast: thread %p (pid %d, %s)", td, p->p_pid,
  151             p->p_comm);
  152         KASSERT(TRAPF_USERMODE(framep), ("ast in kernel mode"));
  153         WITNESS_WARN(WARN_PANIC, NULL, "Returning to user mode");
  154         mtx_assert(&Giant, MA_NOTOWNED);
  155         THREAD_LOCK_ASSERT(td, MA_NOTOWNED);
  156         td->td_frame = framep;
  157         td->td_pticks = 0;
  158 
  159         /*
  160          * This updates the td_flag's for the checks below in one
  161          * "atomic" operation with turning off the astpending flag.
  162          * If another AST is triggered while we are handling the
  163          * AST's saved in flags, the astpending flag will be set and
  164          * ast() will be called again.
  165          */
  166         thread_lock(td);
  167         flags = td->td_flags;
  168         td->td_flags &= ~(TDF_ASTPENDING | TDF_NEEDSIGCHK | TDF_NEEDSUSPCHK |
  169             TDF_NEEDRESCHED | TDF_ALRMPEND | TDF_PROFPEND | TDF_MACPEND);
  170         thread_unlock(td);
  171         PCPU_INC(cnt.v_trap);
  172 
  173         if (td->td_ucred != p->p_ucred) 
  174                 cred_update_thread(td);
  175         if (td->td_pflags & TDP_OWEUPC && p->p_flag & P_PROFIL) {
  176                 addupc_task(td, td->td_profil_addr, td->td_profil_ticks);
  177                 td->td_profil_ticks = 0;
  178                 td->td_pflags &= ~TDP_OWEUPC;
  179         }
  180         if (flags & TDF_ALRMPEND) {
  181                 PROC_LOCK(p);
  182                 psignal(p, SIGVTALRM);
  183                 PROC_UNLOCK(p);
  184         }
  185 #if defined(DEV_NPX) && !defined(SMP)
  186         if (PCPU_GET(curpcb)->pcb_flags & PCB_NPXTRAP) {
  187                 atomic_clear_int(&PCPU_GET(curpcb)->pcb_flags,
  188                     PCB_NPXTRAP);
  189                 ucode = npxtrap();
  190                 if (ucode != -1) {
  191                         ksiginfo_init_trap(&ksi);
  192                         ksi.ksi_signo = SIGFPE;
  193                         ksi.ksi_code = ucode;
  194                         trapsignal(td, &ksi);
  195                 }
  196         }
  197 #endif
  198         if (flags & TDF_PROFPEND) {
  199                 PROC_LOCK(p);
  200                 psignal(p, SIGPROF);
  201                 PROC_UNLOCK(p);
  202         }
  203 #ifdef MAC
  204         if (flags & TDF_MACPEND)
  205                 mac_thread_userret(td);
  206 #endif
  207         if (flags & TDF_NEEDRESCHED) {
  208 #ifdef KTRACE
  209                 if (KTRPOINT(td, KTR_CSW))
  210                         ktrcsw(1, 1);
  211 #endif
  212                 thread_lock(td);
  213                 sched_prio(td, td->td_user_pri);
  214                 mi_switch(SW_INVOL | SWT_NEEDRESCHED, NULL);
  215                 thread_unlock(td);
  216 #ifdef KTRACE
  217                 if (KTRPOINT(td, KTR_CSW))
  218                         ktrcsw(0, 1);
  219 #endif
  220         }
  221         if (flags & TDF_NEEDSIGCHK) {
  222                 PROC_LOCK(p);
  223                 mtx_lock(&p->p_sigacts->ps_mtx);
  224                 while ((sig = cursig(td, SIG_STOP_ALLOWED)) != 0)
  225                         postsig(sig);
  226                 mtx_unlock(&p->p_sigacts->ps_mtx);
  227                 PROC_UNLOCK(p);
  228         }
  229         /*
  230          * We need to check to see if we have to exit or wait due to a
  231          * single threading requirement or some other STOP condition.
  232          */
  233         if (flags & TDF_NEEDSUSPCHK) {
  234                 PROC_LOCK(p);
  235                 thread_suspend_check(0);
  236                 PROC_UNLOCK(p);
  237         }
  238 
  239         userret(td, framep);
  240         mtx_assert(&Giant, MA_NOTOWNED);
  241 }

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FreeBSD/Linux Kernel Cross Reference sys/kern/subr_trap.c

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sys/kern/subr_trap.c